A recent significant advancement in the field of generating low temperature refrigeration is the development of cryocoolers such as the pulse tube cryocooler system wherein pulse energy is converted to refrigeration using an oscillating gas. Such systems can generate refrigeration to very low levels sufficient, for example, to liquefy helium. One important application of the refrigeration generated by such cryocooler systems is in magnetic resonance imaging systems. Other such cryocooler systems are Gifford-McMahon cryocoolers and Stirling cryocoolers.
One problem with conventional cryocooler systems is a potential inefficiency due to a mismatch between the most efficient operating frequency of the cryocooler system and the most efficient operating frequency of the oscillating gas generating system.
Accordingly it is an object of this invention to provide an improved cryocooler system which has more efficient operation.